This invention relates to a waveform measuring and analyzing apparatus having a digital memory means in which digitized waveform samples are stored and having display means reading said memory means and visually displaying the stored waveform.
Oscilloscopes and transient recorders are employed in the measurement and analysis of changing physical phenomena. The changes being analyzed may be repetitive or transient. Generally, a transducer develops an analog voltage signal in accordance with a sensed physical phenomena.
Digital oscilloscopes and transient recorders include means for digitizing a waveform signal, storing such digitized data in a digital memory and reproducing a replica of the signal from such stored data.
A particularly satisfactory and improved waveform measuring and analyzing instrument incorporating all the characteristics of digital oscilloscopes and transient recorders and in addition a resident signal processing capability is disclosed in the copending application of Frederick A. Rose entitled "WAVEFORM MEASURING MEANS WITH RESIDENT PROGRAMMED PROCESSOR FOR CONTROLLED WAVEFORM DISPLAY AND WAVEFORM DATA REDUCTION AND CALCULATION" filed on Mar. 26, 1976, with Ser. No. 670,703, and assigned to the same assignee.
As more fully disclosed in the above application, the instrument includes a digital memory unit to store digitized waveform samples for display on a monitor oscilloscope or CRT screen. The most current digitized data is introduced into the memory location corresponding to the right edge of the display means and old data is erased from the left edge as the new data comes in. During display, the waveform thus marches across the screen from right to left. The memory unit is preferably constructed with a plurality of sections in which different waveforms may be stored. The display unit is operable to display such waveforms in vertically spaced relation on the screen for proper analysis of the physical event. A display selection control permits user selection of the memory sections for display. The memory unit and the display unit include suitable controllers for writing and reading memory data with the data transferred over a controlled hardwired interface for rapid transfer. The instrument further includes a resident, special programmed processor having a read/write connection to the memory unit. An integrated interactive keyboard is also provided for user operated data reduction and includes user operated keys which actuate the resident processor to execute an appropriate one of a plurality of corresponding program routines in the processor memory to do appropriate data reduction and calculation on the waveform array data in memory. The reduced waveform data is stored in an appropriately sized memory array of the memory unit.
The memory unit is preferably a random access memory having memory locations in which the waveform values are stored and are sequentially read by a display interfacing means which operates the display means. For various waveforms, different sized arrays may be desirable. However, to provide such different sized arrays would significantly increase the cost of the memory.